The Paris climate agreement is on the brink of coming into force after 31 nations officially joined the landmark accord, with the United Nations secretary general, Ban Ki-moon, predicting it will be fully ratified by the end of the year.

On Wednesday, 31 countries formally signed up to the Paris deal at the UN general assembly in New York. They include Brazil, the world’s seventh largest emitter of greenhouse gases, Mexico, Argentina and Sri Lanka. Oil-rich United Arab Emirates also ratified the deal, as did nations considered particularly vulnerable to sea level rise, such as Kiribati and Bangladesh.

A total of 55 nations representing at least 55% of global emissions need to sign up for the deal to come into force. The first of these thresholds has now been reached, with Ban and the US secretary of state, John Kerry, both predicting that the agreement will be fully implemented within months.

“I’m ever more confident that the Paris agreement will enter into force this year,” Ban said. “I appeal to all leaders to accelerate domestic arrangements to join this year.

“What once seemed impossible now seems inevitable. When this year ends, I hope we can all look back with pride knowing that we seized the opportunity to protect our common home.”

Video messages from Germany, France, the EU, Canada, Australia and South Korea among others all promised to ratify the Paris accord in the coming months. Should these promises be fulfilled, the agreement will pass the second threshold and come into force.

Australia, one of the largest per capita emitters, will make its “best endeavours to ratify” in 2016, said the country’s prime minister, Malcolm Turnbull. Barbara Hendricks, the German environment minister, said her country planned to ratify the deal “well ahead” of the next UN climate meeting in Marrakesh in November. The UK has made a similar commitment.

Kerry said it was an “exciting moment” but warned that the threat posed by climate change grows every day.

“The problem we continue to confront is growing,” he said. “Each day the planet is on this course, it becomes more dangerous.

“If anyone doubted the science, all they have to do is watch, sense, feel what is happening in the world today. High temperatures are already having consequences, people are dying in the heat, people lack water, we already have climate refugees.”

Kerry added that international climate negotiations have been a “long and frustrating path” since 1992 but that the Paris deal means that they are “finally becoming a story that we are proud to tell our grandchildren and future generations”.

The UN climate change chief, Patricia Espinosa, said: “This is an extraordinary momentum by nations and a clear signal of their determination to implement Paris now and raise ambition over the decades to come.”

A total of 195 nations put their name to the Paris deal and submitted promises to curb their greenhouse gas emissions. Several analyses have cast doubt over whether the pledged emissions cuts will be sufficient to prevent a 2C temperature increase, with concerns exacerbated by record-breaking heat experienced over the course of 2016

The warmest August on record was recorded last month, the National Oceanic and Atmospheric Administration confirmed on Tuesday. The US government agency said last month was the 16th month in a row where temperature records were broken, with July being the single warmest month since modern record keeping began in 1880.

But climate campaigners have said that the speed of the Paris deal ratification raises hopes that the world is finally swinging behind efforts to reduce emissions and prevent the worst ravages of a warming planet.

“The global community is rallying behind swift and ambitious action to combat climate change,” said Paula Caballero, global director of the World Resources Institute’s climate program.

“The fact that the Paris agreement will likely enter into force this year took everyone by surprise. This rapid pace reflects a spirit of cooperation rarely seen on a global scale.

“Today we pause and celebrate the important progress towards bringing the Paris agreement into force. Then we again pick up our shovels and continue the hard work of creating a safer and more prosperous planet.”